1. Field of the Invention
The present invention relates to a lock nut device which is used for various sorts of machines, materials, tools and the like, where a nut is threadedly engaged with a threaded shaft to lock the threaded shaft with a machine, material, tool, or the like.
2. Description of the Prior Art
In the prior art, as a lock nut device, where a nut is to be threadedly engaged with a shaft to be locked, a lock nut device, using a dividing type nut is proposed as, for example, in JP-A 9-72327, JP-A 6-280840 and JP-U 6-1827. Also, although not a lock nut device, a fastener having a threaded part divided in two is shown in U.S. Pat. No. 5,090,857 and U.S. Pat. No. 5,226,678.
The device in JP-A 9-72327 includes a structure where a nut main body has an inner screw and two slits in axial direction and a non-slide surface or an outer screw is provided on a part of a taper outer wall surface of the nut main body, an outside body has a non-slide surface or an inner screw, to be fitted to the non-slide surface or threadedly engaged with the outer screw of the nut main body, and the nut main body is grasped utilizing the engagement of the non-slide surface or the inner screw of the outside body with the non-slide surface or the outer screw of the main body, thereby the threaded engagement and grasping state between the screw shaft and the inner screw of the nut main body is secured and the nut main body is locked. However, since the structure of the nut main body is not a completely dividing type, there is a problem that the grasping force is limited, or when the nut main body is to be fitted to the screw shaft, the nut main body must be inserted from the end portion of the screw shaft and, inevitably, can not be simply fitted from the outside of the screw shaft to any position.
The device in JP-A 6-280840 includes an outside body of nut-like external shape having an inner wall part of taper shape, with the diameter decreasing, gradually, toward one small-diameter opening and having a slit formed in the longitudinal direction at the side of the other large-diameter opening; split nuts, divided in two, with an outside surface of taper shape corresponding to the inner wall part of taper shape of the outside body having a screw formed on an inside wall surface and having an operation arm projected to be engaged with the slit; and a coil spring for energizing the split nuts toward the inner wall part side of taper shape within the outside body, where the split nuts are pressed into the outside body of nut-like external shape through a mounting ring and the coil spring. However, since the lock nut device is complicated in the structure and the number of parts, such as, a coil spring, a cover, or the like, is increased and the operation arm is projected at the split nuts, there is a problem and the machining of the split nuts is difficult.
Further, the device in JP-U 6-1827 has structure that split nuts, divided in two, are arranged within a case with an inner circumferential surface formed in taper, and a suspension bolt is threadedly engaged with the split nuts. An operation part, extending to the outside, is projected from each split nut and is fitted to a groove hole bored on the case, and the split nuts are moved in the axial direction of the case and in the radius direction by the guide action of the inner circumferential surface in taper shape of the case, thereby, the suspension bolt is fixed. However, because the case of the device is fixed to the lower surface of the ceiling panel and the suspension bolt is suspended and threadedly engaged there, the application area is limited and there is a problem that the lock nut can not be locked generally at any position of the bolt or the screw shaft.